MULTIPLE INFECTIONS WITH NEMATOSPIROIDES DUBIUS IN MICE SELECTED FOR LIABILITY TO A SINGLE INFECTION

Abstract

The faecal egg counts and worm burdens of mice selected over 7 generations as refractory (R), random (Rd) or liable (L) to primary infection with Nemataspiroides dubius were significantly different, but the antibody titres (generation 8 mice) after 21 days infection were similar, demonstrating that selection had separated populations of mice which differed in their innate immunity. Variations in adaptive immunity were also shown between the three colonies in terms of protection after challenge infections, self-cure reactions, humoral antibody titres and ability of immune serum from R, Rd and L donors to passively protect recipient Quackenbush (Q) strain mice. R mice were more refractory to primary infection and more proficient in acquiring protective levels of adaptive immunity than L colony mice. Correlation of the faecal parasite egg count after primary with that after secondary infection supported the conclusion that the genetic control of liability to primary infection and of the adaptive immune response following challenge infections were at least partially linked.